Question

Two tuning forks, A and B, produce notes of frequencies f and 260 Hz. If number of beats heard by a person is 8, what can be the possible value of 'f'?
1. 268 Hz
2. 252 Hz
3. Both 1 and 2
4. Neither 1 nor 2

Answer 1

Correct Answer - Option 3 : Both 1 and 2

​CONCEPT:

• Beat: The combination of two waves of slightly different frequencies, perceived as a periodic variation whose rate is the difference of the two frequencies.

Beat frequency (b) = |f1 - f2|

Where f1 and f2 are two frequencies.

CALCULATION:

Given that fA = f and fB = 262 Hz

Since it produces 8 beats

b = 8

b = | fA - fB |

8 = | f - 260 |

remove modulus sign

±8 = f - 260

f = 268Hz or 252 Hz

So the correct answer is option 3.